I'm sure every one has a local car wash all the other grime and crap in the corners is easily removed with what your local car wash may call engine degreaser, and no your car dose not have to be running to spray it just make sure if you have a short ram intake that you take the filter off and get some of the water out of it. Don't be affraid to blast it good with the sprayer never once did I have a problem cleaning my engine on my old dc2 and it cleans up the engine really good. Oh and also make sure to rinse it off.